Freeman Dyson And The Origin Of Life

Freeman Dyson is a brilliant, iconoclastic physicist. In 1985 he was invited to give the Gifford Lectures. Dyson's lectures are collected in a book, "Infinite In All Directions" online here.  I discussed Dyson's description of Natural Theology and the conflict between science and religion, in an earlier post here and how his experience with "nuclear winter" might explain the reaction of many of scientists to climate change  here.


Dyson introduces an interesting theory about the origins of life. He begins by arguing that life is characterized by two important functions: metabolism and replication. Metabolism is the process by which a life form acquires the energy and material needed to sustain itself; replication is the process by which a life form makes copies of itself.


How did life arise? How did the first creature become able to metabolize and reproduce? Dyson argues that there were two events, not one:

Either life began only once, with the functions of replication and metabolism already present in rudimentary form and linked together from the beginning. Or life began twice, with two separate kinds of creatures, one kind capable of metabolism without exact replication, the other kind capable of replication without metabolism. If life began twice, the first beginning must have been with proteins, the second beginning with nucleic acids. The first protein creatures might have existed independently for a long time, eating and growing and gradually evolving a more and more efficient metabolic apparatus. The nucleic acid creatures must have been obligatory parasites from the start, preying upon the protein creatures and using the products of protein metabolism to achieve their own replication.

Hosts must exist before there can be parasites. The survival of hosts is a precondition for the survival of parasites. Somebody must eat and grow to provide a home for those who only replicate. In the living world, as in the world of human society and economics, we cannot all be parasites.